The present invention relates to an improved ski, and more particularly relates to an improved core structure of a ski having a remarkably enhanced impedance against direct transfer of impact load imposed on the ski to the skier's feet.
A ski is generally comprised of top and bottom structures fixedly sandwiching a core structure and most of the conventional core structures are provided with relatively homogeneous internal constructions which are well suited for smooth transmission of elastic waves therethrough due to absence of discontinuity in material and construction. Even in cases where the internal construction of the core structure is more or less discontinuous, e.g. in the case of a plyboard construction, the material composing the whole core structure is homogeneous in the mechanical property thereof, which is again well suited for smooth transmission of elastic waves therethrough. In some cases, the components forming the plyboard construction are made of a material having a relatively low Young's modulus such as ABS resin, which particularly allows easy transmission of elastic waves therethrough.
As is well known, various impact loads act on the ski during skiing and the impact loads so imposed on the ski, more particularly on the bottom structure of the ski, are transferred to the skier's feet taking the form of impulsive elastic waves transmitted through the core structure of the ski.
The above-described low impedance against elastic waves transmission characteristic to the conventional core structure thus naturally allows smooth transmission of the impulsive elastic waves generated by impact loads imposed of the ski without any substantial damping of the impact loads. Such direct and intact transfer of the impact loads to skier's feet cause undesirable fatigue and, in extreme cases, damage to the skier's feet, and gives the skier a disgruntled "feel".